perf: reduce allocations in encode, normalize, compare, and url-converter

- Reuse shared URLSearchParams instance in encodeQualifierParam instead
  of allocating per call
- Cache compiled wildcard regexes in matchWildcard via Map
- Return empty array constant instead of Object.entries({}) for
  undefined qualifiers
- Move URL type support arrays to module-level Set constants

Author: jdalton

src/compare.ts

@@ -28,23 +28,29 @@ function toCanonicalString(input: PurlInput): string {
   return input.toString()
 }
 
+/**
+ * Cache for compiled wildcard regexes to avoid recompilation on repeated calls.
+ */
+const wildcardRegexCache = new Map<string, RegExp>()
+
 /**
  * Simple wildcard matcher for PURL components.
  * Supports * (match any chars), ? (match single char), ** (match anything including empty).
  * Designed for version strings and package names, not file paths.
  */
 function matchWildcard(pattern: string, value: string): boolean {
-  // Convert glob pattern to regex
-  // Escape regex special chars except * and ?
-  let regexPattern = pattern
-    .replace(/[.+^${}()|[\]\\]/g, '\\$&')
-    .replace(/\*/g, '.*')
-    .replace(/\?/g, '.')
-
-  // Anchor to start and end
-  regexPattern = `^${regexPattern}$`
-
-  const regex = new RegExp(regexPattern)
+  let regex = wildcardRegexCache.get(pattern)
+  if (regex === undefined) {
+    // Convert glob pattern to regex
+    // Escape regex special chars except * and ?
+    const regexPattern = pattern
+      .replace(/[.+^${}()|[\]\\]/g, '\\$&')
+      .replace(/\*/g, '.*')
+      .replace(/\?/g, '.')
+
+    regex = new RegExp(`^${regexPattern}$`)
+    wildcardRegexCache.set(pattern, regex)
+  }
   return regex.test(value)
 }
 

src/encode.ts

@@ -3,6 +3,7 @@
  * Provides special handling for names, namespaces, versions, qualifiers, and subpaths.
  */
 import {
+  REUSED_SEARCH_PARAMS,
   REUSED_SEARCH_PARAMS_KEY,
   REUSED_SEARCH_PARAMS_OFFSET,
 } from './constants.js'
@@ -41,13 +42,12 @@ function encodeQualifierParam(param: unknown): string {
     const value = prepareValueForSearchParams(param)
     // Use URLSearchParams#set to preserve plus signs
     // https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams#preserving_plus_signs
-    // Use a local instance to avoid mutation issues in concurrent scenarios
-    const searchParams = new URLSearchParams()
-    searchParams.set(REUSED_SEARCH_PARAMS_KEY, value)
+    // Reuse shared instance — JS is single-threaded so no concurrent mutation issues
+    REUSED_SEARCH_PARAMS.set(REUSED_SEARCH_PARAMS_KEY, value)
     // Param key and value are encoded with `percentEncodeSet` of
     // 'application/x-www-form-urlencoded' and `spaceAsPlus` of `true`
     // https://url.spec.whatwg.org/#urlencoded-serializing
-    const search = searchParams.toString()
+    const search = REUSED_SEARCH_PARAMS.toString()
     return normalizeSearchParamsEncoding(
       search.slice(REUSED_SEARCH_PARAMS_OFFSET),
     )

src/normalize.ts

@@ -5,6 +5,8 @@
 import { isObject } from './objects.js'
 import { isBlank } from './strings.js'
 
+const EMPTY_ENTRIES: Iterable<[string, string]> = []
+
 import type { QualifiersObject } from './purl-component.js'
 
 /**
@@ -146,7 +148,7 @@ function qualifiersToEntries(
   }
   return typeof rawQualifiers === 'string'
     ? new URLSearchParams(rawQualifiers).entries()
-    : Object.entries({})
+    : EMPTY_ENTRIES
 }
 
 /**

src/url-converter.ts

@@ -65,6 +65,52 @@ export interface DownloadUrl {
  * const downloadUrl = UrlConverter.toDownloadUrl(purl)
  * ```
  */
+const DOWNLOAD_URL_TYPES = new Set([
+  'cargo',
+  'composer',
+  'conda',
+  'gem',
+  'golang',
+  'hex',
+  'maven',
+  'npm',
+  'nuget',
+  'pub',
+  'pypi',
+])
+
+const REPOSITORY_URL_TYPES = new Set([
+  'bioconductor',
+  'bitbucket',
+  'cargo',
+  'chrome',
+  'clojars',
+  'cocoapods',
+  'composer',
+  'conan',
+  'conda',
+  'cpan',
+  'deno',
+  'docker',
+  'elm',
+  'gem',
+  'github',
+  'gitlab',
+  'golang',
+  'hackage',
+  'hex',
+  'homebrew',
+  'huggingface',
+  'luarocks',
+  'maven',
+  'npm',
+  'nuget',
+  'pub',
+  'pypi',
+  'swift',
+  'vscode',
+])
+
 export class UrlConverter {
   /**
    * Get all available URLs for a PackageURL.
@@ -89,20 +135,7 @@ export class UrlConverter {
    * conversion logic implemented.
    */
   static supportsDownloadUrl(type: string): boolean {
-    const supportedTypes = [
-      'cargo',
-      'composer',
-      'conda',
-      'gem',
-      'golang',
-      'hex',
-      'maven',
-      'npm',
-      'nuget',
-      'pub',
-      'pypi',
-    ]
-    return supportedTypes.includes(type)
+    return DOWNLOAD_URL_TYPES.has(type)
   }
 
   /**
@@ -112,38 +145,7 @@ export class UrlConverter {
    * conversion logic implemented.
    */
   static supportsRepositoryUrl(type: string): boolean {
-    const supportedTypes = [
-      'bioconductor',
-      'bitbucket',
-      'cargo',
-      'chrome',
-      'clojars',
-      'cocoapods',
-      'composer',
-      'conan',
-      'conda',
-      'cpan',
-      'deno',
-      'docker',
-      'elm',
-      'gem',
-      'github',
-      'gitlab',
-      'golang',
-      'hackage',
-      'hex',
-      'homebrew',
-      'huggingface',
-      'luarocks',
-      'maven',
-      'npm',
-      'nuget',
-      'pub',
-      'pypi',
-      'swift',
-      'vscode',
-    ]
-    return supportedTypes.includes(type)
+    return REPOSITORY_URL_TYPES.has(type)
   }
 
   /**